Galvanizing flux compositions and processes



Patented Sept. 6, 1949 UNITED STATES OFFICE GALVANIZING FLUX COMPOSITIONS AND PROCESSES No Drawing. Application February 3, 1945, Serial No. 576,162

6 Claims.

This invention relates to galvanizing fluxes and processes and more particularly to novel foaming fluxes having excellent fluidity and comprising a chloride, selected from the group consisting of ammonium chloride and zinc ammonium chloride, and an condensation product of formaldehyde corresponding to the formula CHnOH R (BHZOH in which R and R represent hydrogen, alkyl, amino, dimethylolacetyl, alpha dimethylol propionyl, or methylol groups, and is further particularly directed to galvanizing processes employing such fluxes.

In galvanizing practice it is customary to add a small amount of an organic material to the ammonium chloride or Zinc ammonium chloride flux to produce a frothy layer on the surface of the molten metal in the galvanizing pot. A flux which in use forms such a frothy layer is known as a foaming flux. Organic materials commonly used to cause foaming are bran, glycerol, tallow, or sawdust. Inclusion of a foaming agent in a flux is ordinarily considered desirable because it retards decomposition of the flux, preheats incoming articles, and reduces spattering of molten metal.

Unfortunately, the foaming agents hitherto widely used have the disadvantage that after a period of use they thicken the flux and cause it to become viscous. This loss in fluidity is objectionable for a number of reasons. It retards the rate of wetting of the incoming work by the flux, which often results in failure to obtain complete coverage of the work and leads to imperfect galvanizing. It increases the rate at which flux is carried out on the finished work and complicates subsequent cleaning. It makes proper handling of the flux much more diflicult. These and other objections to a viscous flux have caused some galvanizers in certain situations to prefer a nonfoaming flux, despite the known advantages of foaming fluxes.

According to the present invention it has been found that by adding certain condensation products to ammonium chloride or zinc ammonium chloride there are produced galvanizing fluxes which are of the foaming type but which remain remarkably fluid during use. The condensation products effective to produce this result are condensation products of formaldehyde corresponding to the formula CHaOH HQOH in which R and R represent hydrogen, alkyl, amino, dimethylolacetyl, alpha-dimethylol-propionyl, or methylol groups. A further aspect of the invention consists of galvanizing processes employing such fluxes. The processes enjoy the advantages attending the use of a foaming flux but are not subject to the disadvantages heretofore ordinarily encountered. Moreover, by the use of a prepared flux composition of this invention the necessity for the galvanizer to determine the quantity of foamer to use is avoided.

To make a flux of this invention there is added to a major proportion of ammonium chloride or zinc ammonium chloride a minor proportion of a condensation product as a foamer. If too large a proportion of the foaming agent is used the flux will foam excessively and be diflicult to use,

while if the proportion is too small the advantages of the invention will not be fully realized. It has been found that the foaming agents herein described are extremely efiective and it is preferred to employ about from 0.1 to 1.0 per cent by Weight based on the ammonium chloride or zinc ammonium chloride.

The foamer may be added to the molten ammonium chloride or zinc ammonium chloride fluxing agent on the molten metal in the gal vanizing pot. However, this involves the problem of distribution; that is, time and attention is required to insure a uniform distribution of the foamer throughout the fluxing agent. It is therefore preferred to incorporate the foamer in the fluxing agent prior to adding the flux to the galvanizing pot. This may be done by adding the foamer to the granular ammonium chloride or zinc ammonium chloride with mechanical agitation as, for instance, in a tumble mill. The

products so produced are fluxes of maximum economy which can be used in the galvanizing plant with assurance of uniformity and without the close supervision attending the proportionin of the ingredients at the point of use.

The compounds employed as foamers in the fiuxing compositions of this invention are either available commercially, for instance, pentaerythritol, or may easily be prepared by the condensation of formaldehyde with a suitable agent according to practices with which the art is already familiar.

In the following table are shown several examples of compounds which have been found to be effective as foamers in the fluxes of this invention, together with their structural formulae, their method of preparation, and the concentration of the agent, by weight, required in a zinc ammonium chloride flux to give a froth on a galvanizing bath during use equivalent to the froth produced by 0.75% glycerol, 2. foamer heretofore commonly used.

Into the flux compartment of a job galvanizing pot, on the surface of the molten zine, there was placed a quantity of a flux of this invention sufilcient to produce a frothy layer about inches deep. The flux used consisted of zinc ammonium chloride containing 0.37% of its weight of pentaerythritol. Initially the molten flux layer had a viscosity of about centipoises.

Compound g gf Formula gg gg ggg 0 Hz 0H Pentaerythritol 0. 37 H O CHz-( -CE [z 0H Acetaldehyde. I

0 Hz 0H 0 H: OH Ethyl Trln ethylol Methane. 0. C 2H5( JC HBOH Butyraldehyde.

0 Hz 0 H C H2 0 H Methyl Trimethylol Methane 0. 66 0 H3O 'CH2OH Propionaldehyde.

C H: O H

C HzOH 'Iriinethylol Amino Methane 0. 44 H O CHg-G-NH: Nitromethane.

OHROH O H: 2-. Amino-2-Methy1 1,3 Propanediol 0. 76 H 0 CH-.-( JCHQOH Nitroethane.

l'ea

H 0 CH2 CH2 OH 1-1,3-3 Tetramethylol 2-propanone O. 48 H-OO-CH Acetone.

H O 3H: C) ('3H: 0 H

0 H5 amt-2.3mm 1,3 propanediol 0.67 noon,-c':-on,on Nitroethane.

H O 0 H2 C H2O H 1-1,3-3-Tetramethylol 2-butanone 0. 48 H3O-C--C-CH Methyl ethyl ketone.

H 0 CH3 4% HHO H HO CH2 CHzOH 2-2A-4-Tetra-Methylol 3-Pentanone 0. 55 H3OCCCCH3 Diethyl ketone.

H O C JH O C H OH H O CH; CHZOH 1-l,3-3 Tetramethylol 2-heptanone 0. H( JCC-( 0H1) CH3 Methyl amyl ketone.

H O 3H2 g OHQOH The foregoing compounds are all condensation products of formaldehyde and correspond to the formula CHzOH HJOH in which R and R representhydrogen, alkyl, amino, dimethylolacetyl, alpha-dimethylol-propionyl, or methylol groups. In the case of p ent-aerythritol. for instance, R and R both represent methylol groups. In the-case of ethyl trimethylol methane, R. represents an aliphatic The galvanizing pot and flux bath were then used for galvanizing a quantity of iron pipe, the pipe being introduced into the molten zinc by passing through the frothing flux, then being passed beneath a dam holding back the flux, and being removed from the pot Without again passing through the flux. During the operation additional flux was added as required to maintain the flux layer at its original depth. At the end of eight hours of such operation the viscosity of the flux had risen to 200 centipoises but the flux was still sufiiciently fluid to be effective, that is, it was still a live flux.

For comparison, a similar operation was conducted in the same equipment under the same conditions and on the same type of work but using a zinc ammonium chloride flux containing 0.75% of glycerin as a foaming agent. Although this flux had about the same initial viscosity. viz. 43 cps, it was found that more frequent additions of flux during use were required to maintain the desired foam blanket, and after six hours the viscosity had risen to 240 cps. and the flux was considered dead. During the six hour period of use the quantity of flux added to this bath was greater than that added in the case of the pentaerythritol-containing flux during the corresponding period.

The work produced using the pentaerythritolcontaining flux was uniformly well galvanized, being remarkably free of flux spots.

While in the foregoing description of this invention there have been shown certain particular compositions and processes, it will be understood that without departing from the spirit of the invention one skilled in the art may employ numerous compositions and processes.

I claim:

1. A foaming-type galvanizing flux consisting essentially of zinc ammonium chloride and pentaerythritol, the proportion of pentaerythritol being about from 0.1 to 1.0% by weight of the zinc ammonium chloride.

2. In a galvanizing process, the step comprising subjecting the work to be galvanized to contact with a flux consisting essentially of zinc ammonium chloride and pentaerythritol, the proportion of pentaerythritol being about from 0.1 to 1.0% by weight of the zinc ammonium chloride.

3. A foaming-type galvanizing flux consisting essentially of a fiuxing agent selected from the group consisting of ammonium chloride and zinc ammonium chloride and about from 0.1 to 1.0% by weight based on the weight of fiuxing agent, of a composition selected from the group consisting of pentaerythritol, ethyl trimethylol methane, methyl trimethylol methane, trimethylol amino methane, 2-amino-2-methyl 1,3 propanediol, 1-1,3-3 tetramethylol Z-propanone, 2- amino-Z-ethyl 1,3 propanediol, 1-1,3-3-tetramethylol 2-butanone, 2-2,4-4 tetramethylol 3- pentanone, and 1-l,3-3 tetramethylol 2-heptanone.

4. A foaming-type galvanizing flux consisting essentially of zinc ammonium chloride and about from 0.1 to 1.0% by weight based on the Weight of zinc ammonium chloride, of a composition selected from the group consisting of pentaerythrltol, ethyl trimethylol methane, methyl trimethylol methane, trimethylol amino methane, 2-amino-2-methyl 1,3 propanediol, 1-1,3-3 tetramethylol 2-propanone, 2-amino-2-ethyl 1,3 propanediol, 1 1,3 3 tetramethylol 2 butanone, 2-2,4-4 tetramethylol 3-pentanone, and 1-l,3-3 tetramethylol 2-heptanone.

5. In a galvanizing process, the step comprising subjecting the work to be galvanized to contact with a flux consisting essentially of a fiuxing agent selected from the group consisting of ammonium chloride and. zinc ammonium chloride and about 0.1 to 0.0% by weight based on the weight of fluxing agent, of a composition selected from the group consisting of pentaerythritol, ethyl trimethylol methane, methyl trimethylol methane, trimethylol amino methane, 2-amino- 2-methyl 1,3 propanediol, 1-1,3-3 tetramethylol Z-propanone, 2-amino-2-ethyl 1,3 propanediol, l-1,3-3-tetramethylol 2-butanone, 2-2,4-4 tetramethylol 3-pentanone, and 1-1,3-3 tetramethylol 2-heptanone.

6. In a galvanizing process, the step comprising subjecting the work to be galvanized to contact with a flux consisting essentially of zinc ammonium chloride and about from 0.1 to 1.0% by weight based on the weight of zinc ammonium chloride, of a composition selected from the group consisting of pentaerythritol, ethyl trimethylol methane, methyl trimethylol methane, trimethylol amino methane, 2-amino-2-methyl 1,3 propanediol, 1-1,3-3 tetramethylol, 2-propanone, 2- amino-Z-ethyl 1,3 propanediol, 1-1,3-3-tetramethylol 2-butanone, 2-2,4-4 tetramethylol 3- pentanone, and 1-1,3-3 tetramethylol 2-heptanone.

CHARLES A. VANA.

REFERENCES CITED UNITED STATES PATENTS Name Date Kepfer Feb. 23, 1943 Number H. s. WERTZ CATHODE-RAY DEVICE Sept.- 6,

Filed Oct. 12, 1945 2 Sheets-Sheet 1 LINEAR s INPUT WE'EP CIRCUIT LINEAR swssp CIRCUIT T0 RESISTOR 50 FIG. 3

INVENTOR H. S. .WERTZ A T TQRNE Y Certificate of Correction September 6, 1949 Patent No. 2,481,457

CHARLES A. VANA It is hereby certified that errors appear in the printe numbered patent requiring correction as follows:

Columns 3 and 4, in the table, third column thereof, opp

ylol Methane for that portion of the formula reading CH=(J-OH:OH read CHr-J-{HLOH l .0% read 1.0%; s Patent should be read with these corrections therein that the record of the case in the Patent Office.

31st day of January, A. D. 1950.

d specification of the above osite Methyl Trimethcolumn 6, line 18, for 0 "Tue that the said Letter the same may conform to Signed and sealed this THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

